Bohr Diagrams of Ions

• Noble gases do not form compounds because they have a perfectly fill outer orbit. This electron arrangement makes them very stable and so they do not react.

Ne

10 Protons (+) 10 Electrons (-)

• When elements form compounds, changes occur in the arrangement of electrons in the outer orbit.

• Electrons are gained or lost so that atom can have a stable electron arrangement

• Atoms prefer a completely filled outer shell with electrons

• In order for a compound to be stable, it must have a completely filled outer electron orbit

• The outer most electrons of an atom are called VALENCE electrons

Positive and Negative Ions

Arrangement of the outer orbit electrons of metals and non-metals

Metal Non Metal

Metal’s outer shell are nearly empty

Non-Metal’s outer shell are nearly full

Metals • Tend to lose electrons when they combine with other elements

to form positive ions (cations) : note the cat in the word.—> think Paws like positive.

Metal Ion

Example • Sodium: Na ! Na+1

Na Na

+1

Try to make a Bohr Ion for calcium.

Calcium

Ca4020

Non-Metals• Non-metals – Tend to have 4, 5, 6, or 7 electrons in their outer orbits.

• They gain electrons to form negative ions called (anions)

• They gain electrons, thus they have the same fill electron arrangement as a Noble gas.

• Example • Fluorine : F ! F-

F F

1-

Try to make a Bohr-Rutherford ion for phosphorous.

P3115 3-Phosphorous

Metals will often form bonds with non metals.

This is do to metals losing electrons and becoming + charged while non metals gain electrons and becoming - charged.